HIGH-PERFORMANCE
MT SERIES
TRANSCODER
WIRELESS MADE SIMPLE
®
MT SERIES TRANSCODER DATA GUIDE
DESCRIPTION
0.309
MT Series transcoders are designed for bi-
(7.85)
directional remote control applications.
0.207 (5.25)
0.026
Eight status lines can be set up in any
(0.65)
combination of inputs and outputs for the
transfer of button or contact states. An
automatic confirmation indicates that the
transmission was successfully received.
0.284
The large, twenty-four bit address size
(7.20)
0.013
makes transmissions highly unique,
(0.32)
minimizing the possibility of conflict
between multiple devices. The MT also
outputs the ID of the originating transcoder
for logging or identification. Recognition of
the individual outputs can be easily
defined for each device by the
manufacturer or end user. This allows the
creation of user groups and relationships.
0.007
0.030
(0.18)
A Serial Interface Engine (SIE) is provided,
(0.75)
which allows configuration and editing of
the device and control of the transcoder by
Figure 1: Package Dimensions
an external microprocessor or PC. Housed
in a tiny 20-pin SSOP package, MT Series parts feature low supply voltage, current
consumption, and selectable baud rates.
C
Ro
HS
OMP
IAN
T
L
LICAL-TRC-MT
YYWWNNN
FEATURES
APPLICATIONS INCLUDE
Bi-directional control
Keyless Entry
Automatic confirmation
Door and Gate Openers
Security Systems
Secure 2
24
possible addresses
Remote Device Control
8 status lines
Car Alarms / Starters
Serial Interface Engine (SIE)
Home / Industrial Automation
Latched and/or momentary outputs
Remote Status Monitoring
Definable recognition authority
Paging
Transmitter ID output
Custom data transfer
ORDERING INFORMATION
Device targeting
DESCRIPTION
Wide 2.0 to 5.5V operating voltage
PART #
MT Transcoder
Low supply current (370µA @ 3V)
LICAL-TRC-MT
MDEV-LICAL-MT
MT Master Development System
True serial encoding
MT transcoders are shipped in reels of 1,600
Selectable baud rates
No programming required
Revised 4/25/08
ELECTRICAL SPECIFICATIONS
Parameter
POWER SUPPLY
Operating Voltage
Supply Current:
At 2.0V V
CC
At 3.0V V
CC
At 5.0V V
CC
Power-Down Current:
At 2.0V V
CC
At 3.0V V
CC
At 5.0V V
CC
TRANSCODER SECTION
Input Low
Input High
Output Low
Output High
Input Sink Current
Output Drive Current
ENVIRONMENTAL
Operating Temperature Range
V
CC
I
CC
2.0
–
–
–
I
PDN
–
–
–
V
IL
V
IH
V
OL
V
OH
–
–
–
-40
–
+85
°C
–
0.0
0.8 x V
CC
–
V
CC
- 0.7
–
–
–
–
–
–
–
–
0.2 x V
CC
V
CC
0.6
–
25
25
V
V
V
V
mA
mA
2
3
–
–
–
–
0.15
0.20
0.35
1.2
1.5
1.8
µA
µA
µA
–
–
–
340
500
800
450
700
1,200
µA
µA
µA
1
1
1
–
5.5
VDC
–
Designation
Min.
Typical
Max.
Units
Notes
RECOMMENDED PAD LAYOUT
The MT Series transcoders are implemented in an industry standard 20-pin
Shrink Small Outline Package (20-SSOP). The recommended layout dimensions
are shown below.
0.047
(1.19)
0.016
(0.41)
0.026
(0.65)
0.234 (5.94)
0.328 (8.33)
Table 1: Electrical Specifications
Figure 2: PCB Layout Dimensions
Notes
1. Current consumption with no active loads.
2. For 3V supply, (0.2 x 3.0) = 0.6V max.
3. For 3V supply, (0.8 x 3.0) = 2.4V min.
PRODUCTION CONSIDERATIONS
These surface-mount components are designed to comply with standard reflow
production methods. The recommended reflow profile is shown below and
should not be exceeded, as permanent damage to the part may result.
Lead-Free
Sn
/ Pb
275
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V
CC
Any Input or Output Pin
Max. Current Sourced By Output Pins
Max. Current Sunk By Input Pins
Max. Current Into V
CC
Max. Current Out Of GND
Operating Temperature
Storage Temperature
-0.3
-0.3
to
+6.5
to V
CC
+ 0.3
25
25
250
300
to
+85
to
+150
-40
-65
VDC
VDC
mA
mA
mA
mA
°C
°C
250
225
200
260°C Max
240°C Max
TEMPERATURE (°C)
175
150
125
100
75
50
25
0
0
20
40
60
80
100
120
*NOTE*
Exceeding any of the limits of this section may lead to permanent
damage to the device. Furthermore, extended operation at these maximum
ratings may reduce the life of this device.
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
TIME (SECONDS)
Figure 3: MT Series Reflow Profile
*CAUTION*
This product is a static-sensitive component. Always wear an ESD
wrist strap and observe proper ESD handling procedures when
working with this device. Failure to observe this precaution may
result in device damage or failure.
Page 2
Page 3
PIN ASSIGNMENTS
D0 - D7
PIN DESCRIPTIONS
1
2
3
4
5
6
7
8
9
10
VCC
LICAL-TRC-MT
GND
D6
D5
D7
D4
CRT/LRN
D3
ENC_SEL
LATCH
SER_IO
SEL_BAUD
CONFIRM
MODE_IND
TR_PDN
D2
TR_SEL
D1
TR_DATA
D0
CRT/LRN
ENC_SEL
SER_IO
Confirm
Description
Positive Power Supply
Status Control Lines
Create / Learn Mode Activation Line
Encoder Only Select Line
Serial Interface Line
O
O
O
I/O
14
15
16
20
O
I
I
—
Transmission Confirmation Line
Transceiver Power Control Line
Transceiver Mode Control Line
Transceiver Data Line
Mode Indicator Output
Baud Rate Selection Line
Set Latched Outputs
Ground
20
19
18
17
16
15
14
13
12
11
The transcoder has eight status lines, D0 through D7. These lines can be set as
either inputs to record the state of switches or as outputs which will reproduce
switch states upon reception of a valid transmission.
When this line goes high, the transcoder will enter Learn Mode. If it is held high
for ten seconds, the transcoder will clear its memory. If it goes high while the
ENC_SEL line is high, the transcoder will enter Create Mode. If it goes high while
the SER_IO line is high, the transcoder will enter Serial Mode.
If this line is tied high, it will operate as an encoder only. If it is tied low, the
transcoder will default to a decoder until it is set as a transcoder in Create Mode.
This line is used for the Serial Interface Engine, which allows the transcoder to
be programmed by an external device. The transcoder will also use this line to
output the ID of the originating transcoder, status line states, and custom data.
Figure 4: MT Series Transcoder Pin Assignments
Pin Name
V
CC
1
2, 3, 11-13, 17-19
4
5
6
7
8
9
10
I/O
I
I
I/O
—
D0-D7
CRT/LRN
ENC_SEL
SER_IO
CONFIRM
TR_PDN
TR_SEL
TR_DATA
MODE_IND
SEL_BAUD
LATCH
GND
Pin Number
I/O
This line will go high when the transcoder receives a confirmation that its
transmission was received correctly.
TR_PDN
This line can be used to automatically control power to an external transceiver.
When waiting for data the transcoder will toggle power to a transceiver at a 10%
on to 90% off ratio. The times are determined by the selected baud rate.
TR_SEL
This line will toggle an external transceiver between transmit mode (high) and
receive mode (low).
TR_DATA
MODE_IND
This line will send data to and receive data from an external transceiver.
This line will switch when a valid transmission is received, when Learn Mode or
Create Mode is entered, and when the memory is cleared. This allows for the
connection of a LED to indicate to the user that these events have taken place.
SEL_BAUD
NOTE:
None of the input lines have internal pull-up or pull-down resistors. The input lines must always be in a known
state (either GND or V
CC
) at all times or the operation may not be predictable. The designer must ensure that
the input lines are never floating, either by using external resistors, by tying the lines directly to GND or V
CC
,
or by use of other circuits to control the line state.
This line is used to select the baud rate of the serial data stream. If the line is
high, the baud rate will be 28,800bps, if it is low, the baud rate will be 9,600bps.
The baud rate must be set before power up. The transcoder will not recognize
any change in the baud rate setting after it is on.
LATCH
Page 4
If this line is low, then the data outputs will be momentary (active for as long as
a valid signal is received). If this line is high, the outputs will be latched (when a
signal is received to make a particular data line high, it will remain high until
another transmission is received instructing it to go low) by default, but individual
status lines can be set as latched or momentary through the SIE.
Page 5
OVERVIEW
Many products and applications call for the transfer of button presses or switch
closures across a wireless link. Traditionally, a remote control link has operated
in only one direction, from a transmitter to a receiver. The cost associated with
transceivers has been too high to practically implement in low-cost products.
With the increasing availability of low-cost transceiver solutions, bi-directional
links are now practical and open a new world of opportunity.
In a wireless environment, maintaining the reliability and uniqueness of a
transmitted signal is generally of great importance. In a unidirectional system, IC
devices called encoders and decoders are often utilized to simplify this process.
The encoder side turns the status of a number of input lines into an encoded
serial bit-stream output intended for transmission via an RF or infrared link. Once
received, the decoder decodes, error checks, and analyzes the transmission. If
the transmission is authenticated, the decoder’s output lines are set to replicate
the status of the encoder’s input lines.
To accommodate bi-directional links, a new type of device has been developed.
Called a transcoder, this device combines a remote control encoder and decoder
into a single device, and is capable of sending commands as well as receiving
them. It is also able to receive an automatic confirmation from the remote side
indicating that its command was received and the appropriate action was taken.
For example, verifying that an automobile’s doors are all closed and have locked,
or a remote valve has actually closed.
The Linx MT Series is a revolutionary transcoder product designed for wireless
remote control applications. The same device can be used as an encoder,
decoder, or transcoder and is ideal for both uni- and bidirectional applications
and even mixtures of the two. The MT Series is easily implemented, making it
ideal for even the most basic applications, but its rich feature set also allows it to
meet the needs of far more complex applications. These features include the
ability to identify the originating transmitter, establish user permissions, select
output latch modes on a “per pin” basis, and a powerful serial interface that
allows control and information exchange with external microcontrollers or a PC.
Consider a brief example of how just one of the MT’s innovative features could
be used to transform a relatively simple application, the common garage door
opener. In competitive devices, encoded transmissions are generally either
recognized or denied based on the address. If the addresses match, the state of
all data lines will be recognized and output. The MT Series allows a user or
manufacturer to establish a user identity and profile that determines which inputs
will be acknowledged. Let’s apply this capability practically to our example: a
three door garage houses Dad’s Corvette, Mom’s Mercedes, and Son’s Yugo.
With most competitive products, any user’s keyfob could open any garage door
as long as the addresses match. In a Linx MT-based system, each individual
keyfob could easily be configured to open only certain doors (guess which one
Son gets to open!)
As you review this data guide keep in mind that it seeks to cover the full scope
of the MT’s capabilities. The implementation for a simple one button remote will
be different than a powerful targeted control, command, or status network. While
it is unlikely that all of the features of this part will be utilized at any one time, their
availability provides great design flexibility and opens up many new opportunities
for product innovation.
Page 6
TRANSCEIVER POWER CONTROL
The transcoder has the option to control power to an external transceiver through
the TR_PDN line. This line can be connected to a power down or supply line of
a Linx transceiver or a similar input on another transceiver. This allows the
transcoder to power down the transceiver when it is not required, thereby
reducing current consumption and prolonging battery life.
The transcoder pulls the TR_SEL line low to place the transceiver into receive
mode and looks for valid data for 16mS or 32mS, depending on the baud rate. If
data is present on the TR_DATA line, then the transcoder enters Receive Mode.
If no data is present, then the transcoder pulls the TR_PDN line low to power
down the transceiver and goes to sleep for 150mS or 295mS. The “off” time is
approximately nine times the “on” time, resulting in a 10% duty cycle, greatly
reducing the transceiver’s current consumption. However, there may be a lag
time from when the transmitting transcoder activates to when the receiving
transcoder responds. The transcoder enters Receive Mode when it sees a valid
packet, so there would only be a lag for the first packet.
This cycle continues until data is received placing the transcoder into Receive
Mode, until a status input line is taken high placing it into Transmit Mode, or the
CRT/LRN line is taken high placing it into Serial, Learn, or Create Modes. If a
faster response time is desired, then the TR_PDN line can be left disconnected.
OPERATION WITH THE MS SERIES
The MT Series transcoders are fully compatible with the MS Series encoders
and decoders. Tying the ENC_SEL line high makes the transcoder operate just
like an MS Series encoder. Tying this line low enables it to become an MS
decoder or a transcoder, depending on how it is set-up. This is described in detail
in the Transcoder Operation section.
There are two important issues of note when using the transcoders with the MS
Series. First, only two of the MS baud rates are supported by the MT; 9,600bps
and 28,800bps. Second, the MS Series will not respond to the advanced
features of the MT, like the custom data and Targeted Device Addressing.
The main advantage offered by the MT over the MS is the serial interface. This
allows a number of advanced options to be realized. Some other advantages
are:
• More users (60 vs. 40)
• Automatic confirmation
• The lower duty cycle (25% vs. 50%) of the MT Series allows for greater range
in countries like the United States that average transmitter output power over
time.
• The serial output on every packet instead of just once per receive session.
• Allows existing receive stations using the MS Series decoder to be upgraded to
take advantage of the advanced features without having to upgrade existing
transmitter stations based on the MS Series encoder.
• Mixed MS / MT-based systems that allow cost savings for units that only require
unidirectional operation while other units require bidirectional operation.
Page 7
TRANSCODER OPERATION
Table 4: MT Series Transcoder Serial Interface Engine Timings (mS)
Restore Default
(9,600bps)
Restore Default
(28,800bps)
Table 3: MT Series Transcoder Restore Default Serial Interface Engine Command
Table 2: MT Series Mode Definitions
Restore Default
Defined
(After Create Mode)
Default
(From Factory)
Set-Up
When the transcoder powers on for the first time, it is in a default set-up. When
in this mode, the transcoder looks at the state of the ENC_SEL line on power-
up. If the line is high, then the transcoder enters Default Encoder Mode and acts
like an encoder only. It pulls the TR_SEL line high to set the transceiver into
transmit mode and makes all of its status lines inputs. It will use a default
address that is set at the factory.
Definition
Definition
ENC_SEL is High
ENC_SEL is Low
ENC_SEL is Low
ENC_SEL is High
Power-Up State
If the ENC_SEL line is low, then the transcoder enters Default Decoder Mode
and acts like a decoder only. It pulls the TR_SEL line low to set the transceiver
into receive mode and makes all of its status lines outputs. At this point, the User
Access is open, so the transcoder accepts
all
valid transmissions, regardless of
address. This allows the designer to set up an external database for learned
users and control permissions. The designer is free to set up a system of their
choosing. External parts can be used with the transcoder to give the end product
more memory to increase the number of users and more processing speed have
a faster response time when scanning through the user list. In this mode, the
transcoders become a data pipe around which a designer can create a larger,
more complicated system than can be implemented with the transcoders alone.
The User Access can be locked simply by learning a user. From this point on, it
requires that the transmission have a valid, learned address before it will
respond. Only a Restore Default commend sent on the serial interface will place
the transcoder back into Default Decoder Mode. This command removes all
existing settings and restores the transcoder to the factory default condition.
Once an address has been created, the transcoder enters a Defined set-up. The
state of the ENC_SEL on power-up also determines the mode of operation in this
set-up. If the ENC_SEL line is high, the transcoder enters Defined Encoder
Mode. The process of creating an address also defines which status lines are
inputs and which are outputs. In this mode, the transcoder acts as an encoder
only using just the defined inputs and the address that was created.
If the ENC_SEL line is low, the transcoder enters Transcoder Mode and uses
both the inputs and outputs as well as the defined address. In this mode, it can
send commands as well as receive commands. As above, the User Access is
open until a user is learned into memory.
Table 2 shows the different modes and how they are entered.
If the transcoder has been previously set up, through creating an address and
learning users, then the saved settings are applied and the transcoder enters the
appropriate mode based on the state of the ENC_SEL line.
The transcoder then sets the baud rate according to the state of the SEL_BAUD
line and goes to sleep until an action on one of its inputs places it into another
mode.
In summary, there are two key points in the initial operation of the transcoders:
• Prior to Create Mode, all of the status lines will be either inputs or outputs
depending on the state of the ENC_SEL line when the transcoder is powered
on.
• Prior to Learn Mode, any valid MS or MT style packet will activate the status line
outputs.
Page 8
Min Ready Max Ready Receive Cmd Process Cmd Reply Wait Transmit Reply Finish Process Min Total Time Max Total Time
0.08
17.00
2.80
1.07
4.00
1.73
870.00
880.00
900.00
0.08
33.00
8.30
1.07
4.00
5.29
870.00
890.00
925.00
0x00 -
0xFF
- 0x52 - 0x73 - 0x74 - 0x4D - 0x54 - 0xFF
Transcoder Mode
Defined Encoder Mode Encoder only using defined inputs and address
Default Decoder Mode All status lines are outputs
Default Encoder Mode All status lines are inputs, default address
SER_IO = Input
SER_IO = Output
Mode
Command
Transcoder using defined inputs, outputs, and
address
Description
0x00 - 0x41 - 0x43 - 0x4B - 0xFF
Open
Any valid packet activates outputs
(From Factory)
Locked
Only authorized users are allowed
(After Learn Mode)
Open
(From Factory)
Locked
Only authorized users are allowed
(After Learn Mode)
User Access
Reply
Any valid packet activates outputs
Page 9
Description
